Sulfactive aldehyde hydrogenation catalyst



Nov. 19, 1957 ALDEHYDE R. B. MAsoN f l-:T AL 2,813,911

SULFACTIVE ALDEHYDE HYDROGENATION CATALYST Filed Aug. 21, 1953 I l A IIll E \\\t H 2N au@ H fz 5 Qcllph Ea. mason. @mentare b5 MM? Chaam-msUnited States Patent O SULFACTIVE ALDEHYDE HYDRGENATION CATALYST RalphB. Mason and Edward W. S. Nicholson, Baton Rouge, La., assignors to EssoResearch and Engineering Company, a corporation of Delaware ApplicationAugust 21, 1953, Serial No. 375,591

3 Claims. (Cl. 260-638) The present invention relates to the preparationof oxygenated organic compounds by the reaction of car-` bon monoxideand hydrogen with carbon compounds containing olenic linkages in thepresence of carbonylation catalysts. More specifically, the presentinvention relates to the preparation of alcohols of a high degree ofpurity suitable for the preparation of colorless plasticizing agentsfrom the aldehydes formed in the first stage of the process. Still moreparticularly, the present invention relates to an improved process forpreparing the sulfur-insensitive hydrogenation catalyst to increase itsactivity and decrease the extent of contaminants and impurities in theresulting alcohol product.

The synthesis of oxygenated organic compounds from olelinic compoundsand mixtures of CO and H2 in the presence of a catalyst containingmetals of the iron group, particularly cobalt, is now well known. In thefirst stage, the olenic material, catalyst, and CO and H2 are reacted atsuperatmospheric pressures to give a product consisting essentially ofaldehydes containing one more carbon atom than the reacted olefin. Thisoxygenated organic mixture, which contains in solution salts andcarbonyls of the catalyst, i. e. cobalt carbonyl, is treated in acatalyst removal zone at elevated temperatures to cause removal of themetal carbonyls. The catalyst-free material is then hydrogenated to thecorresponding alcohol, and it is to this stage that the presentinvention applies.

This carbonylation reaction provides a particularly attractive methodfor preparting valuable primary alcohols, particularly those which areintermediates for plasticizers and detergents. Amenable to the reactionare substantially all types of organic compounds, substituted or not,which contain olenic unsaturation.

The catalyst for the first stage of the reaction, where olenic materialis converted into aldehyde, is usually added in the form of salts of thecatalytically active metal with high molecular weight organic acids,such as oleic, stearic, naphthenic, etc. Examples of such catalyst saltsor soaps are cobalt stearate, naphthenate and the like. These salts aresoluble in the liquid olefin or olefin-paraflin feed, and may besupplied to the first stage dislsolved in the feed or as hydrocarbonsolution.

As the synthesis gases are consumed at equivalent or equimolar rates,synthesis gas components are usually added at equimolar proportions ofH2 and CO, though it has been suggested to use both an excess ofhydrogen and an excess of CO. The conditions for reacting oleniccompounds with hydrogen and carbon monoxide vary somewhat in accordancewith the nature of the olenic feed, but the reaction is generallyconducted at pressures of about 3000 pounds per sq. in. and attemperatures in the range of about 20D-450 F. The ratio of synthesis gasfeed to olen may vary Widely; in general, about 1000 to 15,000 cu. ft.of H2|CO per barrel olen feed are employed.

Following the carbonylation stage, the aldehyde prodl solved catalyst inthe form of carbonyls, is treated at material.

elevated temperatures in the presence of a gas, vapor, or liquid todecompose the carbonyl to an oil-insoluble form of the metal.Thereafter, the aldehyde product is freed of suspended catalyst, and ispassed to a hydrogenation zone for conversion into alcohols.

The hydrogenation stage may be operated at conditions includingtemperatures and pressures and feed rates of the same order of magnitudeas those obtaining in the carbonylation stage. Various types ofcatalysts may be employed in the reaction. However, serious diicultieshave been encountered in the hydrogenation catalyst, whensulfur-sensitive catalysts, such as nickel and the like are employed inthis service. The most readily available oleflnic feed stocks areselected hydrocarbon streams derived from petroleum sources, and thesefrequently have sulfur contents of 0.1% and even higher. Similarly, thesynthesis gases employed in the carbonylation zone are frequentlycontaminated with minor amounts of sulfur impurities.

Appreciable sulfur which is present in the crude reaction mixturecontaining the carbonyl compounds is carried through the oxonation andcarbonylation stage into the hydrogenation stage, where it combines withthe hydrogenationcatalyst, if the latter is sulfur-sensitive, to reduceand destroy its activity.

Extensive experimental work with sulfur-insensitive catalysts showedthat the great majority either had unsatisfactory activity or alcoholselectivity, or had insucient mechanical strength, or all of theseundesirable properties. However, it was found that a catalyst consistingessentially of molybdenum sulfide supported on activated carbon combinedsatisfactory mechanical strength with good activity and high alcoholselectivity, and was far superior to other sulfur-insensitivehydrogenation catalysts for liquid phase hydrogenation `ofsulfur-contaminated aldehyde product resulting from the carbonylationreaction. The catalyst was prepared by impregnating activated char, inthe form of 4 8 mesh granules, with an aqueous solution of ammoniummolybdate, heated to decompose the molybdate to the corresponding oxide,MoO3 and sulided with H28 to convert the oxide to the sulfide.

Though the sulfur-insensitive catalyst thus produced has the greatadvantage of long life, physical strength and resistance to poisoning bycarbon monoxide and sulfur, it suffers the disadvantage of permittingsome sulfur to pass unchanged through the hydrogenation zone.Furthermore, it has been observed that when the catalyst is freshlysulded, there is a pronounced tendency to introduce additional sulfurinto the alcohol product. The amounts are relatively small, in the orderof a few parts per million, and, in most operations, as where 4detergentalcohols are to be produced, would cause no difficulties. But in thecase where alcohols are prepared for utilization as plasticizerintermediates, these small amounts of sulfur play an important role indegrading the product and making it unfit for use as a plasticizer. Inparticular, the octyl and nonyl alcohols are favored as plasticizingagents in the form of their esters, such as phthalates, adipates,maleates and the like. It is a condition precedent that for their use asplasticizers for light or colorless resins and clear plastics that theybe substantially colorless.

lt has been found that extremely small amounts of sulfur in the alcoholproduct, on the order of less than a thousandth of a percent, aresufficient to make the alcohol unfit for plasticizing purposes. Thus ithas been found that where the alcohol product has a sulfur content ofonly 15 parts per million, i. e. 0.00l5%, the phthalate esterificationproduct was too dark for use as a plasticizing This, darkening occursduring the;recycling 3 operation during 'esteriiication Thus in atypical alcohol recycle esterification operation, a l-2% molal excess ofalcohol is used based on phthalic anhydride. Unreacted alcohol isstripped oif from the ester product under reduced pressures and-blendedwith Afresh 'alcohohfor re- A cycle to thev esterification zone.tWhenmorethan about *parts per million 4olf-sulfur contaminants 'arepresent ^infthe alcoholp1'oduct,'it has lbeen'found that `color formingbodiesbuild-'up lin "the recycle'rnaterial during ythe recycle stage.

I' In brief, therefore, small amounts vof'sulfur in the alco- -holproduct'to be'employed, in `the manufacture Vof plas- -ticizingintermediatesplay'an importantrolein degrading the product,'resultingfin an economic loss.

'Contaminationhas beentraced in part to Vliberation of sulfur fromI"thesulfactivemolybdenum hydrogenation catalyst in the `-earlystagesAofthe operation. The catalyst is prepared yand M603 `convertedessentially completely' to'thesulde.

lWhen'thecatalystthus prepared is employedin vthecommercial-hydrogenation of aldehydes ,prepared'by car- `"bonylation ofC7 olefins to produce octyl alcohols 'for use 4asplasticizingintermediates, it was :founzdgin a particular operation, that the rst20,000 gallons o'f'Cg alcohols thus lproduced Were'completelyunsuitablefor use asplasticiz- `ing-agent-intermediates.

The alcohol product had a sulfur vcontentdf 19 parts per million, which`Was'found tolpro- `duce `:zm'estercolorof 1.05. The ester color is ameasure *of optical'density of `the ester as produced under prescribedconditions, 'andhas been found'to be affected by Aextremely smallamounts of sulfur impurities. The wave --iengthusedinstudying isooctylphthalate ester is '21470 A. fForlpro'ducing a Asatisfactoryplasticizing ester, the ester lcolorshould not be 'greater thanaboutiOIl. This value is associated with 'product alcohol sulfur contentof 10 -partsfper Vmillion and less.

1It is, therefore, the principal object of 'the present invention toprovide and to prepare an aldehyde hydrogenation catalyst which isinsensitive to .carbon monoxide. and sulfur, but'which will inturn'haveless tendency .to contaminate the resulting alcohol yproductthan sulfactive catalysts hitherto described.

It is also a purpose and object ofthe presentiinvention to prepare in anovelV manner a superior .sulfactive-'aldehyde hydrogenationcatalyst ofhigh.activi-ty,.which reaches a high activity level at alower.temperature.than'sulfactive catalysts prepared by means hithertodescribedin the art.

'Other and further purposes,` obiectsand advantages of the presentinvention will become apparent from the more detailed descriptionhereinafter.

`It has now been found that a molybdenum sulfide-oncharcoal catalyst ofconsiderably greater stability and lessertendency to lose sulfurinitially may be prepared .bysuliiding a form ofmolybdenum oxidewhereinthe molybdenum is in azlower valance state than in the hexavalentform, which it has vbeen the practice to sulfide hitherto.

.In the standard method of preparing the-sultidedcatalyst, as describedhitherto, activated carbonpellet's are impregnated withalhexavalentmolybdenum salt, Vsuch as ammonium molybdate, and thereafter heatedtoconvert .the materialto'MoOs'which is-then sulded. AOn heating:innthepresencexof l-IzS, thesoxide isprobably converted 4initially tothe trisulde which decomposes in the presence of .'heatzto molybdenumdisulfide 'and elementary sulfur. Also, elementary sulfur may resultfrom the reduc'tion'of .the-molybdenum trioxideby theHsS duringtheisulding zstage. :lntether case, elementary sulfur-.isJleft-'onrthe'catalyst and is graduallyremoved by the alcohol 3product during thehydrogenation. This sulfur loss reaches an apparent equilibrium afterabout l5,000-20,000 gallons of alcohol have been produced byhydrogenation and, as pointed out, this initial alcohol product is notsuitable for esterilication purposes, and must be further treated orrerun, after the catalyst has come into equilibrium, because of highsulfur content and high ester color.

.It has now been found that the hydrogenation'catalyst may beconsiderably more quickly and eiiiciently sultided, and the amount ofoff-test alcohol produced in the initial stages of the hydrogenation`reaction be appreciably lessened, by reducing the valence of themolybdenum on the catalyst from the hexavalent form to an intermediatestate before sulding. This is done `byheating the catalyst afterimpregnation to about 200 to 350 F., to decompose the ammoniummolyb'date to molybdenum trioxide, M003. Thereafter, a stream ofhydrogen is introduced at a temperature of about 600 to 1000 F., at apressure of 200-3000'p. s. i. g. for a suicient period of time to reduceM003 to M002, M00, or a mixture of the lower oxides. The sultidedcatalyst, whether prepared from the higher or lower oxides ofmolybdenum, consists yfor the most part o'f MoSz, i. e. Ythe molybdenumis in the quadrivalent state. 4But when the molybdenum is reduced to'the quadrivalent state, or lower, prior to sulding, as in laccordancewith the present invention, the oxidation of hydrogen sulfidev toelementary sulfur is avoided.

Whenthe desiredamount of reduction has been accomplished, the catalystbed is cooled to about 300 F., and H28 is introduced into the bed,either 4asagas or dissolved in an inertliqid, such as Varsol or virginnaphtha. Gas is passed until sultding is complete. Because of theprereduction of vthe catalyst, a shorter time and less HzS are requiredlthan when`MoO3 is suliided.

The present invention and its application will best be Y understoodrfrom the moredetailed,descriptionhereinafter,

invention.

wherein reference Awill be ,made to the accompanying drawing, which is aschematic representation .of a system suitable for carrying out apreferred embodiment of the As the latter ,resides in the hydrogenationrather than in the carbonylationor finishing stages, only the vfirstmentionedstep is.shown in thedrawing.

-Referring now to the drawing, liquid aldehyde product substantiallyfreeof dissolved cobalt, and which may contain in solution as much as 0.005%sulfur, is passed to the lowerportion 4of hydrogenator 2 via line 4.Simulta- 'neously, Hz is supplied to reactor 2 through line 6 inproportions at least suflicient to .convert .thealdehyde Aproductintothe rcorresponding alcohol.

The catalyst Within ,reactor 2 comprises molybdenum sulfide supported onan active carbon carrier prepared as detailed below, `the proportion ofmolybdenum sulde to the carrier being about l to 10%. Hydrogenator Z maybe operated at pressures of about 2500 to 4500 p. s. i. g., and

at temperatures from `about 40G-600 F., ,a liquid feed rate of from0.25-2 v./v./hr., and ahydrogen feed'rate of from SOOO-20,000 cu.ft./bbl. to add to the hydrogenation zone ,up to 8-10% water.

The hydrogenation catalyst/is. preferably first prepared by impregnating3A6" pellets of activated charcoal with ammonium molybdate, and dryingin a steam oven at 250 F. The dried product isltransferred tohydrogenator 2, and heated to 600 to l000 F., in a stream of hydrogenadmitted through line 8. Pressures of 200-3000 p. s. i. g., aremaintained in 2, and the passage of gas is continued until at least partof the M003 formed by the decomposition of the molybdate has beenconverted to the desired mixture Aof MoO and M002; the operation mayalso be controlled to lproduce substantially either of these oxides.Control ofthe extent of reduction is readily maintained by collectingand measuring the amount of 'waterformed v*400 F.andthecatalystsulfided, which may'be carried It is also beneficialoutbypassing-gaseous HaS or HzS dissolved in an inert liquidfsuch asVarsol or virgin naphtha, through the bed until su'liiding is complete.-These materials may also be passed into the -bed through line 8, afterthe hydrogenation has been terminated.

I After. sullii..g, the catalyst is allowed to corne to conditions, theexcess sullding agent is purged, and a `stream of inert hydrocarbon,such as Varsol,l is passed through the bed for several hours.Thereafter, the aldehyde feed is cut in under operating conditionsdescribed above.

The products of the hydrogenation reaction are withdrawn overheadthrough line and passed to the alcohol finishing plant for furtherprocessing in a manner known per se.

The process of the present invention and its results may be furtherillustrated by the following results obtained in a commercial operationwherein isooctyl alcohols were prepared from a heptene fraction. In runA, the catalyst was not reduced prior to suhiding, while in run B, thecatalyst was treated substantially in the manner described heretofore.

The above data clearly show that with the catalyst prepared inaccordance with the present invention, the amount of olf-test alcoholwhich required further processing was cut in half, being reduced from20,000 to 10,000 gallons. Furthermore, the quality of the ofi-testalcohol initially prepared by the new process was considerably betterthan that initially prepared by the process employing the catalystprepared by the former technique and thus requires considerably lessreprocessing to make the alcohol suitable for plasticizing purposes.

It is of interest to note that the initially hydrogenated catalyst had ahydrogenation activity equal to that of the non-prehydrogenated catalystat a considerably lower temperature level. This is a marked advantage.Particularly in the case of the sulfactive catalysts it has been foundthat at the higher temperatures necessary to get good activity, there isa marked tendency to overhydrogenation and conversion of the aldehydedirectly to the hydrocarbon or olen, due to dehydration of the alcoholinitially formed. With the catalyst of the present invention, lowerhydrogenation temperatures may be employed, thus minimizingoverhydrogenation.

The process of the present invention may be modified in manners apparentto those skilled in the art. Thus,

though a hydrogenation catalyst consisting of molybdenum sulde onactivated carbon has been described, the prereducing technique may beapplied to sude catalysts in general, particularly to those containingchromium, tungsten, cobalt and nickel, all of which may have sulfidesexisting in more than one valence state. Similarly, the oxides which areto be suliided may be formed by other known means beside impregnationand heating to decompose the soluble salt. Also, the reduction need notbe carried out to completion, but it is desirable that the metalcomponent of the catalyst be reduced to a state of oxidation as low asin the sulfide form. Also, other suliding agents such as CS2 may beused.

The treatment of the molybdenum oxide with hydrogen prior to suliidingcan be employed with any molybdena preparation. For example, a catalystcomprising approximately equimolar quantities of molybdenum oxide, zincoxide and magnesium oxide was tested in autoclave `operationsafter A(1)sultdi'ng 'without the hydrogen pre- "treatinent'and (2)su`liidin`gfollowing hydrogenreduction at 850 l?.` Data from these operationsare:

Wt. Percent Hydrocarbon. Wt. Percent Intermediate- Wt. Percent Alcohol52 8 Wt. Percent Bottoms To indicate that the amount of sulfurassociated with the prereduced catalyst was substantially smaller thanthat associated with the same catalyst that was not given theprehydrogenation treatment, the following data are shown:

In run E, M003 was treated with H2S, whereas in run F the M003 was rsthydrogenated to a mixture of MoOz and MoO. The final catalyst in bothcases, however, was essentially MoSz, the difference in sulfur contentreilecting and being a measure of the elementary sulfur formed byreduction of the hexavalent molybdenum in run E with HzS.

What is claimed is:

1. In the production of alcohols by reacting olefns with CO and H2 in acarbonylation stage at elevated temperaaldehyde product in the presenceof a hydrogenation catalyst to form an aldehyde product, hydrogenatingsaid aldehyde product in the presence of a hydrogenationcatalyst underliquid phase hydrogenation conditions to form said alcohol product, theimprovement which comprises carrying out said hydrogenation in thepresence of a catalyst consisting essentially of a major proportion ofpreformed activated carbon pellets supporting a minor proportion ofmolybdenum sulfide, said catalyst being prepared by hydrogenatingpellets comprising M003 at 'a temperature of about 600 to 1000 F. and ata pressure of 200 to 3000 p. s. i. g. to convert a substantial portionof said molybdenum to a lower valence state, and thereafter sulding saidhydrogenated product.

2. An improved process for hydrogenating oxo aldehydes which comprisespassing an oxo alcohol product through a reaction zone containing ahydrogenation catalyst while maintaining hydrogenation pressures andtemperatures in the range of about 2500 to 4500 p. s. i. g. and 400 to600 F. respectively, said hydrogenation catalyst having been prepared byimpregnating preformed activated char pellets with ammonia molybdate,heating said impregnated material to convert the molybdate to the oxide,hydrogenating said oxide at a temperature of about 600 to 1000 F. and apressure of about 200 to 3000 p. s. i. g. for a period of timesufficient to convert a substantial portion of said oxide to amolybdenum oxide wherein said molybdenum has a valence lower than thehexavalent molybdenum, thereafter suliding said hydrogenated productwith a suliiding agent ,and recovering from said reaction zone animproved alcohoi product containing substantially no sulfurcontaminants. v

3. A process in accordance with claim 2 wherein extraneous water ispassed into said zone during said aldehyde hydrogenationsreaction..

References Cited in the-nte' of this patent UNITED STATES PATENTS2,432,087 Brown Dec.` 9, 1947

1. IN THE PRODUCTION OF ALCOHOLS BY REACTING OLEFINS WITH CO AND H2 IN ACARBONYLATION STAGE AT ELEVATED TEMPERAALDEHYDE PRODUCT IN THE PRESENCEOF A HYDROGENATION CATALYST TO FORM AN ALDEHYDE PRODUCT, HYDROGENATINGSAID ALDEHYDE PRODUCT IN THE PRESENCE OF A HYDROGENATION CATALYST UNDERLIQUID PHASE HYDROGENATION CONDITIONS TO FORM SAID ALCOHOL PRODUCT, THEIMPROVEMENT WHICH COMPRISES CARRYING OUT SAID HYDROGENATION IN THEPRESENCE OF A CATALYST CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OFPREFORMED ACTIVITED CARBON PELLETS SUPPORTING A MINOR PROPORTION OFMOLYBDENUM SULFIDE, SAID CATALYST BEING PREPARED BY HYDROGENATINGPELLETS COMPRISING MOO3 AT A TEMPERATURE OF ABOUT 600* TO 1000*F. AND ATA PRESSURE OF 200 TO 3000 P.S.I.G. TO CONVERT A SUBSTANTIAL PORTION OFSAID MOLYBDENUM TO A LOWER VALENCE STATE, AND THEREAFTER SULFIDING SAIDHYDROGENATED PRODUCT.